President Trump said he'll begin reinstating nuclear sanctions on the Iranian regime, effectively marking the beginning of the end of the agreement.

President Trump announced Tuesday that he would reimpose nuclear-related sanctions on Iran, setting the stage for a long-expected dismantling of the Obama-era nuclear deal with the Islamic Republic.

“I am announcing today that the United States will withdraw from the Iran nuclear deal,” he said. “In a few moments, I will sign a presidential memorandum to begin reinstating U.S. nuclear sanctions on the Iranian regime.”

On the face of it, the announcement goes much further than had been expected. Observers had expected Trump to decline to waive only the most immediate set of sanctions related to Iran’s oil trade—the sanctions that were specifically at play with the May 12 deadline, giving America’s European allies time to find a fix that would placate the president.

But the White House in a subsequent statement said companies “doing business in Iran will be provided a period of time to allow them to wind down operations in or business involving Iran.” The move is especially striking because even Trump administration officials have previously said Iran is complying with the accord. Speaking to reporters after Trump’s remarks, John Bolton, the president’s national-security adviser, said: “We have announced a withdrawal from the deal. So we’re out of the deal.” He added the president’s decision to impose nuclear-related sanctions means no new contracts will be allowed in the “proscribed areas.”

“For contracts that already exist, there’s a wind-down period to allow an orderly termination of the contract,” he said. This ranges from 90 to 180 days, depending on the commodity involved. Bolton also rejected the idea that the U.S. was violating its commitments to its allies, noting that it had withdrawn from the agreement.

There was an inevitability about Trump’s announcement, which had been expected in some form for months. Trump, as a presidential candidate, had pledged to rip up the agreement that he’d labeled the “worst deal in history.” But his remarks will likely have profound implications for the Middle East, U.S. allies in the region, and America’s European partners, who had lobbied furiously with the Trump administration to preserve the Joint Comprehensive Plan of Action (JCPOA), as the nuclear agreement is officially called. Besides Iran and the United States, the nuclear agreement involves China, France, Germany, Russia, the United Kingdom, and the European Union.

France and the U.K., especially, could face a difficult choice at the United Nations, where they are both permanent, veto-wielding members of the Security Council (along with China and Russia, both of which support the agreement), if Iran decides to refer the U.S. to the UN over its violation of the pact—as the JCPOA’s mechanism allows it to do. Iran will undoubtedly relish the prospect of isolating and embarrassing the United States at an international forum. Whether the Islamic Republic can persuade America’s closest allies to go along is uncertain. A resolution condemning the U.S. for violating the JCPOA is all but dead on arrival at the Security Council, where the U.S. is also a permanent, veto-wielding member, but the very introduction of such a resolution would be an embarrassment for the U.S.

European officials had maintained the agreement was preventing Iran from developing nuclear weapons as intended. The agreement, they said, did not set out to curtail the Islamic Republic’s other actions in the region—its ballistic missile tests, its involvement in the Syrian civil war and in Iraqi politics, its role in the conflict in Yemen, and its continued support for Shia proxies, such as Hezbollah in Lebanon. But it was these activities the deal’s opponents pointed to as the reason to leave it—in their view the deal offered Iran financial benefits in exchange for nuclear restraint without doing enough to check the Islamic Republic in other areas.

French President Emmanuel Macron and German Chancellor Angela Merkel met separately with Trump in late April to lobby for keeping the deal, but Macron told French media he believed Trump “will get rid of this deal on his own, for domestic reasons.” Boris Johnson, the U.K. foreign secretary, even went on Fox News, Trump’s favored network, on Monday, in a last-ditch effort to persuade the president to keep the deal, urging Trump not to “throw the baby out with the bathwater.” In the end, none of it mattered.

A European diplomat, speaking on condition of anonymity, said “there is plainly a difference of opinion” between the two sides. The diplomat said the Europeans believed that Iran could be controlled through the JCPOA, a new stronger, nuclear agreement, pushing back on Iran’s ICBM program, and its activities in the Middle East—the so-called “four pillars” policy.

“What seems to be the intention is for Pillar One to be knocked over,” the European diplomat said. “I think they want to have a new start. And as far as I understand the Trump administration’s intentions, they believe that you cannot build a second pillar—a future JCPOA—as long as the current one is in existence. I won’t hide it from you that we don’t share that analysis.”

Trump said his consultations with allies made it clear “that we cannot prevent an Iranian nuclear bomb under the decaying and rotten structure of the current agreement.”

If supporters of the agreement worked overtime to save it, its critics worked just as furiously. Last week Benjamin Netanyahu, the Israeli prime minister who is a longtime skeptic of the JCPOA, made a public presentation in which he said Israel had uncovered documents showing that Iranian officials had lied when they said the country had never pursued nuclear weapons. He said the Islamic Republic had a detailed plan to develop nuclear weapons—and had hidden the relevant documents away in an archive in Tehran. But few details from his presentation were new—or indeed proved that Iran had cheated on its current international obligations. Trump thought otherwise.

“At the heart of the Iran deal was a giant fiction that a murderous regime desired only a peaceful nuclear energy program,” Trump said. “Today we have definitive proof that this Iranian promise was a lie. Last week, Israel published intelligence documents long concealed by Iran, conclusively showing the Iranian regime and its history of pursuing nuclear weapons.”

Nor was the agreement universally beloved in Iran. The JCPOA—with its sanctions relief and its promise of facilitating investment in Iran—did not create the economic miracle many Iranians had hoped for. Trump’s public distaste for the deal created uncertainty for international businesses that may otherwise have looked to invest in Iran.Iran’s oil sales, which increased after the JCPOA was concluded, will almost certainly be imperiled—though it’s unlikely that countries like China and India, which rely heavily on Iranian crude exports, will alter their plans to keep buying Iranian oil. They and others can now point out that it is the U.S., not Iran, that has violated the deal. (International inspectors have repeatedly found Iran to be in compliance.) But the blow to the already dismal Iranian economy, which had caused months of anti-regime protests, is likely to not only increase those protests, but also embolden Iranian hard-liners who had opposed the JCPOA on the grounds that the Islamic Republic had given away too much in exchange for too little.

In many ways, the debate leading up to the U.S. withdrawal from the deal echoed the one surrounding its entry in July 2015. Just as, once again, discussion focused on issues the JCPOA did not address, the pact’s “sunset” provisions were also, once again, a matter of vigorous argument. Certain restrictions on Iran’s nuclear program expire in eight, 10, and 15 years, which the deal’s opponents argued allows the Islamic Republic to freely resume nuclear-weapons development after those periods. The pact, in this reading, merely delayed the time it would take for Iran to have nuclear weapons. The agreement’s supporters point out that as part of the deal Iran also signed the Non-Proliferation Treaty, under which it commits in perpetuity never to pursue nuclear weapons.

Reflecting the prominence of these concerns even when the deal was signed, congressional critics of the agreement passed legislation to require the president to certify every 120 days that Iran was complying with the JCPOA. While President Obama was only too happy to do this for his signature foreign-policy achievement (Iran’s compliance is certified, under the agreement, by international inspectors), the process of certification became a problem for the deal’s survival after Trump took office in January 2018. The president made public his unhappiness at having to repeatedly certify the deal that he’d called “insane,” but did so anyway for a time, in part, because of advice from Rex Tillerson, his then secretary of state, and James Mattis, the defense secretary. But last October, Trump decertified the agreement, leaving it up to Congress to either come up with a legislative fix or reimpose sanctions on Iran, an action that would have effectively marked the beginning of the end of the agreement. U.S. lawmakers didn’t come up with such a fix—essentially punting the decision back to the White House. Trump had until May 12 to decide whether to waive sanctions as the deal requires if Iran is complying, and he made his announcement four days early.

Trump warned Iran against restarting its nuclear program, saying “it will have bigger problems than it has ever had before.”

He added: “The fact is they are going to want to make a new and lasting deal, one that benefits all of Iran and the Iranian people. When they do, I am ready, willing, and able. Great things can happen for Iran and great things can happen for the peace and stability that we all want in the Middle East.”

Bolton elaborated on those comments. “We’re prepared, along with the Europeans and others, to talk about a much broader deal addressing all of the aspects of Iran’s actions that we find objectionable,” he said. “We’re prepared to do that right now.”

Still, people within the Trump administration defended the deal. On April 26, Mattis told the Senate Armed Services Committee that the JCPOA’s “verification … is actually pretty robust as far as our intrusive ability” to verify whether Iran was complying. “I've read it now three times … and I will say that it is written almost with an assumption that Iran would try to cheat,” he said. Mattis had previously favored staying in what he called an “imperfect” agreement because he said it was in the U.S. national-security interest.

Those debates are now moot, as the countdown clock starts toward the JCPOA’s ultimate demise. If that happens, the agreement will join other Obama-era foreign-policy accomplishments abandoned by the Trump administration, including the Paris climate accord, the Trans-Pacific Partnership trade agreement, and improved relations with Cuba.